It is increasingly common for video camera capabilities to be incorporated into multi-purpose, small and light-weight handheld electronic devices, such as mobile phones, compact cameras and media players. Unlike the larger dedicated-purpose video camcorders, such multi-purpose handheld devices typically lack any mechanical or optical mechanism to reduce jittery video motion due to a shaky or unsteady hand. Due to their lighter weight and typical use of a wide angle lens, the multi-purpose handheld devices can be more susceptible to jittery video motion from hand shakiness. Further, as the availability of these inexpensive multi-purpose handheld devices spreads the popularity of shooting video beyond the community of amateur and professional videographers, consumer video is more and more commonly produced by users with very little training or experience in how to shoot quality video. There is also a growing popularity among consumers to share short video clips over the Internet via email, blogs, video sharing web sites and social networking sites. Particularly for those users who are not videography professionals or hobbyists, the video clips are often uploaded to the web site (sometimes directly from the video capture device) without any editing or other processing. For these various reasons, the quality of video clips shared on the web is very often quite poor, and the video clips commonly suffer from jittery video motion due to hand shakiness.
Digital video image stabilization is a digital signal processing technique that can be applied to video to correct jittery video motion from hand shakiness. In one exemplary implementation, the technique involves calculating local motion estimation for macroblocks of each image of the video sequence relative to its preceding image; processing the local motion vectors of the macroblocks to produce an estimate of the global motion due to jitter; and then compensating for the jittery video motion by digital shifting or warping the image in a direction opposite to the estimated jitter motion.
One drawback of known digital video image stabilization is that the technique is quite computationally intensive. When uploading video to a blog, video sharing web site or social networking site, the video may be uploaded from devices that vary in processing capabilities. Moreover, the casual user may be more interested in immediacy of quickly posting their video to a video sharing or social networking site, such that any time consuming processing of the video is undesirable. For example, video may be uploaded directly from a multi-purpose handheld device, such as over a cellular network. However, the multi-purpose handheld device (such as a mobile phone) often has limited processing resources, or must share processing resources with other capabilities of the multi-purpose device. Alternatively, the handheld device also could be connected to a PC, laptop, netbook or like devices with internet connectivity to upload video to a video sharing or social networking site. However, these internet-connected PCs also vary greatly in processing resources. Also, in the interest of immediacy, any processing delays during posting via an internet-connected device can be undesirable.
For these reasons, a video image stabilization technique that operates effectively across the various available computing platforms would be useful and desired.